Photographic light-sensitive materials containing phosphoric acid ester of aliphatic polyols



United States Patent i 3,443,951 PHOTOGRAPHIC LIGHT-SENSITIVE MATERIALSCONTAINING PHOSPHORIC ACID ESTER OF ALIPHATIC POLYOLS Jozef Willems,Wilrijk-Antwerp, Edwin Frans Hendricx, Boechout, Robrecht Julius Thiers,Brasschaat, and Jozef Jan Onghena, Heverlee, Belgium, assignors toGevaert- Agfa N.V., Mortsel, Belgium, a Belgian company No Drawing.Filed June 30, 1965, Ser. No. 468,614 Claims priority, application GreatBritain, July 2, 1964, 27,346/ 64 Int. Cl. G03c 1/34 U.S. CI. 96-94 7Claims ABSTRACT OF THE DISCLOSURE The formation of spots inradiation-sensitive silver halide material due to the presence ofparticles of heavy metals, compounds of heavy metals and the corrosionproducts of such metals or the compounds inhibited by the incorporationin the material of at least one watersoluble phosphoric acid ester of analiphatic polyol, which per molecule contains at least two phosphoricacid groups from the class of the primary and secondary phosphoric acidgroups. Preferably, the polyol is an aliphatic hydrocarbon polyol.

This invention relates to photographic light-sensitive silver halidematerials containing compounds which prevent the formation of spots bythe presence of particles of heavy metals and/or heavy metal compounds.

Although an utmost care is taken in the manufacture of light-sensitivematerial, it is diflicult to avoid completely the setting down ofparticles of heavy metals, such as iron particles, or of compounds ofheavy metals, such as rust particles, onto the light-sensitive material.Said particles generally originate from the wearing and the corrosion ofthe coating machines, but also traces of these metals or metal compoundsare sometimes present in the photochemicals used or may be present inthe support such as a support of paper, film and glass upon which thelight-senstive emulsion is coated.

Said metal particles or particles of metal compounds are harmfulparticularly because they are chemically reactive, which means that theyexert a secondary action upon the light-sensitive emulsion layer andaggravate the faults which are caused by the presence of said particlesand which are mostly invisible by the unaided eye in such a way thataccording to the nature of the particle and the kind of the emulsionapplied, light and dark spots become visible after treating the exposedlightsensitive material in the photographic baths.

The metal particles in the photographic layers can be affected and thecorrosion products formed can diffuse away from the central nucleus.These corrosion products can exert a sensitizing or descnsitizing actionon the emulsion so that after the normal bath-treatment the photographicmaterial shows black and white spots respectively. Furthermore most ofthese metals or their compounds can act as reductors and cause aspontaneous development which leads to black spots. On the contrary,other influences such as affection of the latent image and hindrance ofthe development lead to white spots. In

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all these cases the resulting spot is always larger than the dustparticle which is the cause of this undesired phenomenon. This caneasily be checked, e.g., by bleaching out with a usual bleaching agentthe silver from the material showing the black spot. Nearly always theblack spot disappears but in the centre a very small nucleus remainswhich can only be seen by enlarging.

Also fine metal particles or dust consisting of metal compounds whichare present in a nonlight-sensitive adjacent layer exert an equallydisadvantageous influence on the upperor underlying light-sensitivelayer. The harmful corrosion products of the metal particles or thedissolved ingredients of the metal compounds indeed can reach bydiffusion the light-sensitive layer to cause the above-mentioned faults.

Hitherto many compounds have already been proposed to prevent thisformation of spots or at least to reduce such formation to a greatextent. All these compounds, however, show one or more of the followingdisadvantages: an insufficient activity, an activity only in determinedemulsions and in a well determined rather small pH range, and theoccasioning of secondary effects on the silver halide emulsion layersuch as desensitisation, fog formation and colouration. Also thephosphoric acid derivatives proposed as spot inhibiting compounds showthese disadvantages. The phosphoric acid derivatives proposed hithertoare mainly alkali metaphosphates, alkali tripolyphosphates and alkalihexametaphosphates either or not mixed with alkali pyrophosphates. Theprimary and secondary alkylor aryl-phosphates and acid alkyloraryl-pyrophosphates incorporated into the light-sensitive silver halidematerial do not even show any spotinhibiting action at all.

In the circumstances, it was very surprising to state that the formationof spots can practically completely be avoided when in at least oneWater-permeable layer lying at the same side of the support as thelight-sensitive silver halide emulsion layer and/or in the supportitself, at least one water-soluble phosphoric acid ester of an aliphaticpolyol is present which contains per molecule at least two phosphoricacid groups from the class of the primary and secondary phosphoric acidgroups. These primary and secondary phosphoric acid groups can likewisebe present in their salt form such as sodium, potassium or "ammoniumsalts or as amines.

These phosphoric acid esters are active in all kinds of light-sensitivesilver halide materials regardless of the pH and the sensitivity of thesilver halide emulsion layer; moreover, they also appear to exert anantistatic and fog-depressing action on the light-sensitive material.

The phosphoric acid esters used according to the present invention canbe prepared in different ways. It is necessary during this preparationto choose the mutual molar proportions of the reagents in such a waythat always two or more primary or secondary phosphoric acid groups areintroduced per molecule of aliphatic polyol. It can be determined in asimple way by potentiometric titration of the said functions presentwhether this has occurred.

A first method of preparation is the reaction of aliphatic polyols withphosphorus pentoxide. Herein mixtures of different compounds are formedwhich contain primary and/or secondary phosphoric acid groups. Moreover,polyphosphate structures are built as well.

There is also the possibility that when two hydroxyl functions are infavourable position, cyclic phosphoric acid esters are formed.

Appropriate phosphoric acid esters can also be prepared byphosphorylation of aliphatic polyols with phosphorus oxychloridefollowed by hydrolysis of the acid chloride formed as an intermediateproduct.

Other processes for the preparation of appropriate phosphoric acidesters are transesterification reactions for instance of monoalkylphosphates with aliphatic polyols.

Also A. J. Kirby (Chem. and Ind. 47 (1963), 1877), describes a processfor the preparation of phosphoric acid esters which are appropriate forbeing applied according to the present invention, viz., a reaction ofphosphorous acid and iodine with polyols.

Aliphatic polyols which are appropriate for the preparation of the saidphosphoric acid esters are among others carbohydrates such as glucose,mannitol, sorbitol, glycerine, 1,4-butanediol, 1,2,4-butanetriol1,2,6-hexanetriol, pentaerythritol, 2,4-dihydroxy-3-(hydroxymethyl)-pentane, 1,1,l-tris(hydroxymethy1)-propane and 4-hydroxy-2-(hydroxymethyl)-n-amy1 alcohol.

The compounds used according to the present invention can be present indifierent concentrations in the support, e.g., a paper support of thelight-sensitive material and/ or in at least one of the water-permeablelayers lying at the same side of the support as the light-sensitivesilver halide emulsion layer. Said concentrations depend among others onthe compound chosen and the nature of the layer wherein the compound ispresent. Preferably the compounds according to the present invention arepresent in the light-sensitive silver halide emulsion layer itself andthis in the most widely varying concentrations ranging from some mg. toand more g. per sq. m. of light-sensitive material. For the case thecompounds are not present in the light-sensitive layer but in anotherlayer, they are nevertheless active since they dilfuse into saidlight-sensitive layer.

The phosphoric acid esters according to the present invention usuallyare first dissolved, e.g., in water. The support can then be soaked withsuch solution for the case that the compounds applied according to thepresent invention are incorporated into the support. If, however, thecompounds are incorporated into a waterpermeable layer, in most casestheir solution is added to the coating composition of the respectivelayer or layers.

In a photographic material, the compounds used according to the presentinvention have the advantage that they do not impair at all the pursuedphotographic properties, such as, e.g., contrast, sensitivity andstability. Consequently, these compounds can be incorporated intohigh-sensitive as well as into low-sensitive emulsions, intohigh-contrast as well as into low-contrast emulsions, into acid as wellas into alkaline emulsions.

A further advantage is that the compounds according to the invention donot impair at all the other products used in the manufacture oflight-sensitive materials such as dispersing agents, colour couplers,surface-active agents, optical bleaching agents, antioxidising agents,sensitisers, fog-inhibiting agents, stabilisers, hardeners orplasticisers.

As a result, the compounds according to this invention can be used inall kinds of photographic negative and positive material, such as, e.g.,printing material, X- ray film, graphic material, infrared-sensitivesilver halide material and material for the application of the silvercomplex diffusion transfer process. Also in photographic light-sensitivematerial not containing silver halide, or in photographicnonlight-sensitive material the phosphoric acid esters described cansuccessfully he used for avoiding spots caused by particles of heavymetal compounds.

The following preparations and examples illustrate the presentinvention.

4 PRODUCT l.REACTION PRODUCT OF SORBI- TOL AND PHOSPHORUS PENTOXIDE Amixture of g. (0.42 mol) of phosphorus pentoxide, 91 g. (0.47 mol) oranhydrous sorbitol and 500 cc. of diethyl ether is refluxed for 7 h. ona water bath, whilst stirring. After standing overnight, the whitecrystalline reaction product is sucked oil. Yield: 150 g. The reactionproduct is hygroscospic and an aqueous solution thereof reacts as astrong acid.

PRODUCT 2.REACTION PRODUCT OF SORBITOL AND (MONO)ETHYLDIHYDROGEN PHOS-PHATE: SORBITOL HEXAKIS(DIHYDROGEN) PHOSPHATE 151 mg. (1.14 mols) of(mono)ethyldihydrogen phosphate, 18.2 g. (0.09 mol) of sorbitol and alittle magnesium powder are heated in a flask on an oil bath, whilst thereaction mass is stirred under nitrogen. The theoretically calculatedamount of ethanol is distilled 01f. Meanwhile the temperature of the oilbath has been increased to 200 C. The excess of (mono)ethyldihydrogenphosphate is removed by washing the reaction mass with anhydrous diethylether. The residue is placed under vacuum on a boiling water bath andthereafter cooled down to room temperature and dissolved in methanol.This solution is filtered over active carbon, and the methanol isdistilled off under reduced pressure on a water 'bath at 40 to 50 C.Yield: 42.5 g. The reaction product is a viscous oil which reacts as anacid.

PRODUCT 3.REACTION PRODUCT OF GLYC- ERINE AND PHOSPHORUS PENTOXIDE 276g. (2.82 mols) of dried glycerin are added in 3 times to a mixture of 59g. (0.42 mol) of phosphorus pentoxide in 500 cc. of anhydrous diethylether at 150 C. The reaction is relatively exothermic. After adding allglycerine and refluxing for 2 h. on the water bath, the diethyl ether isdecanted and the reaction product obtained is dried under vacuum. Yield:320 g. The reaction product is a viscous oil which reacts as a strongacid.

PRODUCT 4.--REACTION PRODUCT OF GLUCOSE AND PHOSPHORUS PENTOXIDE Amixture of 50 g. (0.35 mol) of phosphorus pentoxide, g. (0.47 mol) ofglucose and 500 cc. of diethyl ether is refluxed for 7 h. in a flask ona water bath, whilst thoroughly stirring. After standing overnight, thereaction product is sucked off. Yield: 138 g. The reaction product ishygroscopic and an aqueous solution thereof reacts as a strong acid.

PRODUCT 5.3,9 DIHYDROXY 2,4,8,l0 TETRAOXA-3,9-DIPHOSPHASPIRO[5,5+UNDECANE-3,9- DIOXIDE /OCH: CHzO\ R /i O OCH:OHaO O This product is prepared as described in J. Org. Chem. 28 (1963),1608-1612.

PRODUCT 6.-PENTAERYTHRITOL TETRAKIS (DI-HYDROGEN PHOSPHATE) HO (T) (T)OH P-OCH: CHaOP HO OH HO OH P-O CH: CH:OP

l.\ HO O O OH This product is prepared as described in the U.S. patentspecification 2,583,549, filed Apr. 25, 1950, by G. C. Daul and I. R.Reid.

Example 1 A not yet quite dry adhesive layer applied to a cellulosetriacetate support, is dusted with finely divided iron powder. A strip Aof this treated support is coated with a high-sensitive panchromaticallysensitized silver bromide emulsion. A strip B of this treated support iscoated with the same silver bromide emulsion to which, however, per kg.of emulsion 1 g. of product 1 was added. After driving these two teststrips are exposed in such a way that after developing for 9 min. atroom temperature, fixing and rinsing, a density of 0.6 is obtained. Fordevelopment a solution of the following composition is used:

Water 800 Monomethyl-p-aminophenol sulphate g 2 Sodium sulphite (cryst.)g 200 Hydroquinone g 4 Borax g 2 Water to 1000 cc.

After development, both strips A and B are rinsed for some seconds andthen fixed for min. in a solution of the following composition:

Sodium thiosulphate g 200 Potassium metabisulphite g 25 Water to 1000cc.

The strips are then rised for 30 minutes in running water and finallydried. The strips A shows numerous black spots whereas the strip Bprepared according to the invention shows a uniform appearance and thesame density all over its surface.

Eample 2 Example 1 is repeated but instead of adding product 1 to theemulsion ready for coating, a same amount of product 3 is added thereto.

Example 3 A strip of crude paper A is coated with a barytalayer of thefollowing composition:

50% aqueous barium sulphate suspension kg 2 10% aqueous gelatin solutioncc 1000 Very finely divided metal powder, originating from the coatingmachine g 0.5

Water cc 800 Monomethyl-p-aminophenol sulphate g 1.5 Sodium sulphite(cryst.) g 50 Hydroquinone g 6 Sodium carbonate (cryst.) g 100 Potassiumbromide g 1 Water to 1000 cc.

After rinsing for 5 sec., fixing for 10 min. in a solution as describedin Example 1, rinsing for 1 hour in running water, and drying, thedeveloped paper strip A displays numerous white spots each showing inthe center the applied metal particle, whereas the strip B preparedaccording to the invention shows a uniform appearance and has the samedensity all over its surface.

Example 4 A strip of baryta-coated paper A is prepared as in Example 3.A strip B is prepared in the same way with the same baryta compositionto which, however, per kg. 5 g. of product 5 were added. Bothbaryta-coated strips are coated with a silver chlorobromide emulsionwhich on development gives a warm brown image tone. After developing,fixing and rinsing as in Example 3, numerous white spots are observed onthe paper strip A, whereas the strip B prepared according to theinvention shows a uniform appearance and possesses the same density allover its surface.

Example 5 A strip of crude photographic paper is coated with a barytalayer of the following composition:

50% aqueous barium sulphate suspension kg 2 10% aqueous gelatin solutioncc 1000 The half A of this baryta-coated strip is coated with alight-sensitive contrasty silver bromide emulsion which contains ironpowder. After drying, this strip is exposed in such a way that afterdeveloping for seconds, fixing and rinsing it shows a density of 0.6 Fordevelopment a solution is used as that described in Example 3. The paperstrip is rinsed for 5 sec., fixed for 10 min. in a solution as describedin Eample 1, rinsed for 1 hour in running water and dried. The paperstrip shows numerous white spots.

If to the light-sensitive emulsion, however, 3 g. of product 6 are addedper kg. and if this emulsion is then coated on the half B of thebaryta-coated strip the latter shows after a further treatment as forthe half A a uniform appearance without white spots.

Example 6 Example 5 is repeated but product 6 is replaced by 4 g. ofproduct 1.

Example 7 Example 5 is repeated but product 6 is replaced by 4 g. ofproduct 2.

Example 8 Example 5 is repeated but product 6 is replaced by 4 g. ofproduct 3.

Example 9 Example 5 is repeated but product 6 is replaced by 4 g. ofproduct 4.

Example 10 Example 5 is repeated but product 6 is replaced by 4 g. ofproduct 5.

We claim:

1. Photographic silver halide material sensitive to electromagneticradiation comprising a support and a silver halide layer thereon, saidmaterial having incorporated therein at least one water-solublephosphoric acid ester of an aliphatic polyol, which per moleculecontains at least two phosphoric acid groups from the class of theprimary and secondary phosphoric acid groups, said acid groups being inthe form of the free acid or the water-soluble salts thereof.

2. Photographic light-sensitive silver halide material according toclaim 1, wherein the water-soluble phosphoric acid ester is present inthe light-sensitive silver halide emulsion layer.

3. The material of claim 1 wherein said polyol is an aliphatichydrocarbon polyol.

4. The material of claim 1 including at least one waterpermeable layerin water-permeable relationship with said halide layer on the same sideof the support as said halide layer, said phosphoric acid ester beingpresent in said water-permeable layer.

5. The method of inhibiting the formation in silver halide materialsensitive to electromagnetic radiation of spots caused by the presenceof particles of heavy metals, compounds of heavy metals and thecorrosion products thereof which comprises the step of incorporating insaid material at least one water-soluble phosphoric acid ester of analiphatic polyol, which per molecule contains at least two phosphoricacid groups from the class of the primary and secondary phosphoric acidgroups, said acid groups being in the form of the free acid or thewater-soluble salts thereof.

6. The method according to claim 5, wherein the Watersoluble phosphoricacid ester is present in the light-sensitive silver halide emulsionlayer itself.

aliphatic hydrocarbon polyol.

References Cited UNITED STATES PATENTS 3,169,863 2/1965 Grabhofer et al96-107 3,258,338 6/ 1966 Claeys et a1. 96-94 3,332,777 7/1967Groh-Molnar 96-94 I. TRAVIS BROWN, Primary Examiner.

US. Cl. X.R. 96-85, 87, 109

